What is type 2 diabetes?

Type 2 diabetes, formerly called adult-onset diabetes, is the most common type of diabetes. About 95 percent of people with diabetes have type 2. People can develop type 2 diabetes at any age, even during childhood. However, this type of diabetes develops most often in middle-aged and older people. People who are overweight and inactive are also more likely to develop type 2 diabetes.

In type 2 and other types of diabetes, you have too much glucose, also called sugar, in your blood. People with diabetes have problems converting food to energy. After a meal, food is broken down into glucose, which is carried by your blood to cells throughout your body. With the help of the hormone insulin, cells absorb glucose from your blood and use it for energy. Insulin is made in the pancreas, an organ located behind the stomach.

Insulin is made in the pancreas.

Type 2 diabetes usually begins with insulin resistance, a condition linked to excess weight in which your body’s cells do not use insulin properly. As a result, your body needs more insulin to help glucose enter cells. At first, your pancreas keeps up with the added demand by producing more insulin. But in time, your pancreas loses its ability to produce enough insulin, and blood glucose levels rise.

Over time, high blood glucose damages nerves and blood vessels, leading to problems such as heart disease, stroke, kidney disease, blindness, dental disease, and amputations. Other problems of diabetes may include increased risk of getting other diseases, loss of mobility with aging, depression, and pregnancy problems.

Can type 2 diabetes be delayed or prevented?

Yes. The results of the Diabetes Prevention Program (DPP) proved that weight loss through moderate diet changes and physical activity can delay or prevent type 2 diabetes. The DPP was a federally funded study of 3,234 people at high risk for diabetes. This study showed that a 5-to 7-percent weight loss, which for a 200-pound person would be 10 to 14 pounds, slowed development of type 2 diabetes.

People at High Risk for Diabetes

DPP study participants were overweight and had higher than normal levels of blood glucose, a condition called prediabetes. Many had family members with type 2 diabetes. Prediabetes, obesity, and a family history of diabetes are strong risk factors for type 2 diabetes. About half of the DPP participants were from minority groups with high rates of diabetes, including African Americans, Alaska Natives, American Indians, Asian Americans, Hispanics/Latinos, and Pacific Islander Americans.

DPP participants also included others at high risk for developing type 2 diabetes, such as women with a history of gestational diabetes and people age 60 and older.

Approaches to Preventing Diabetes

The DPP tested three approaches to preventing diabetes:

Making lifestyle changes. People in the lifestyle change group exercised, usually by walking 5 days a week for about 30 minutes a day, and lowered their intake of fat and calories.

Taking the diabetes medicine metformin. Those who took metformin also received information about physical activity and diet.

Receiving education about diabetes. The third group only received information about physical activity and diet and took a placebo—a pill without medicine in it.

People in the lifestyle change group showed the best outcomes. But people who took metformin also benefited. The results showed that by losing an average of 15 pounds in the first year of the study, people in the lifestyle change group reduced their risk of developing type 2 diabetes by 58 percent over 3 years. Lifestyle change was even more effective in those age 60 and older. People in this group reduced their risk by 71 percent. But people in the metformin group also benefited, reducing their risk by 31 percent. More information about the DPP, funded under National Institutes of Health (NIH) clinical trial number NCT00004992, is available at www.bsc.gwu.edu/dpp.

Lasting Results

The Diabetes Prevention Program Outcomes Study (DPPOS) has shown that the benefits of weight loss and metformin last for at least 10 years. The DPPOS has continued to follow most DPP participants since the DPP ended in 2001. The DPPOS showed that 10 years after enrolling in the DPP,

people in the lifestyle change group reduced their risk for developing diabetes by 34 percent

those in the lifestyle change group age 60 or older had even greater benefit, reducing their risk of developing diabetes by 49 percent

participants in the lifestyle change group also had fewer heart and blood vessel disease risk factors, including lower blood pressure and triglyceride levels, even though they took fewer medicines to control their heart disease risk

the metformin group reduced the risk of developing diabetes by 18 percent

Even though controlling your weight with lifestyle changes is challenging, it produces long-term health rewards by lowering your risk for type 2 diabetes, lowering your blood glucose levels, and reducing other heart disease risk factors. More information about the DPPOS, funded under NIH clinical trial number NCT00038727, can be found at www.bsc.gwu.edu/dpp.

People in the lifestyle change group exercised, usually by walking 5 days a week for about 30 minutes a day.

Other Types of Diabetes

In addition to type 2, the other main types of diabetes are type 1 diabetes and gestational diabetes.

Type 1 Diabetes

Type 1 diabetes, formerly called juvenile diabetes, is usually first diagnosed in children, teenagers, and young adults. In this type of diabetes, your pancreas can no longer make insulin because your body’s immune system has attacked and destroyed the cells that make it. Treatment for type 1 diabetes includes taking insulin shots or using an insulin pump, making wise food choices, being physically active on a regular basis, controlling blood pressure and cholesterol, and, for some, taking aspirin daily.

Gestational Diabetes

Gestational diabetes is a type of diabetes that develops only during pregnancy. Hormones produced by your placenta and other pregnancy-related factors contribute to insulin resistance, which occurs in all women during late pregnancy. Insulin resistance increases the amount of insulin needed to control blood glucose levels. If your pancreas can’t produce enough insulin, gestational diabetes occurs.

As with type 2 diabetes, excess weight is linked to gestational diabetes. Overweight or obese women are at particularly high risk for gestational diabetes because they start pregnancy with a higher need for insulin due to insulin resistance. Excessive weight gain during pregnancy may also increase risk. Gestational diabetes occurs more often in some ethnic groups and among women with a family history of diabetes.

Although gestational diabetes usually goes away after the baby is born, a woman who has had gestational diabetes is more likely to develop type 2 diabetes later in life. Babies born to mothers who had gestational diabetes are also more likely to develop obesity and type 2 diabetes as they grow up.

What are the signs and symptoms of type 2 diabetes?

The signs and symptoms of type 2 diabetes can be so mild that you might not even notice them. Nearly 7 million people in the United States have type 2 diabetes and don’t know they have the disease. Many have no signs or symptoms. Some people have symptoms but do not suspect diabetes.

Symptoms include

increased thirst

increased hunger

fatigue

increased urination, especially at night

unexplained weight loss

blurred vision

numbness or tingling in the feet or hands

sores that do not heal

Many people do not find out they have the disease until they have diabetes problems, such as blurred vision or heart trouble. If you find out early that you have diabetes, you can get treatment to prevent damage to your body.

Should I be tested for diabetes and prediabetes?

Anyone 45 years of age or older should consider getting tested for diabetes and prediabetes. If you are 45 or older and overweight—see the body mass index (BMI) chart—getting tested is strongly recommended. If you are younger than 45, overweight, and have one or more other risk factors, you should consider getting tested. Ask your doctor for an A1C test, a fasting blood glucose test, or an oral glucose tolerance test.

Your doctor will tell you if you have normal blood glucose, diabetes, or prediabetes. If you are told you have prediabetes, take steps to prevent type 2 diabetes. And ask your doctor if you should be tested again in 1 year.

What does having prediabetes mean?

Having prediabetes means your blood glucose is higher than normal but not high enough to be diagnosed as diabetes. In 2009, at least 78 million American adults were estimated to have prediabetes. Having prediabetes also means you are at risk for getting type 2 diabetes and heart disease. However, you can reduce your risk of getting diabetes and even return blood glucose levels to normal by losing a little weight through healthy eating and being more physically active.

Does sleep matter?

Yes. Studies show that untreated sleep problems, especially sleep apnea, can increase the risk of type 2 diabetes. Sleep apnea is a common disorder in which you have pauses in breathing or shallow breaths while you sleep. Most people who have sleep apnea don’t know they have it and it often goes undiagnosed. Night shift workers who have problems with sleepiness may also be at increased risk for obesity and type 2 diabetes.

How can I reduce my risk for type 2 diabetes?

You can do a lot to reduce your risk of getting type 2 diabetes. Being more physically active, reducing fat and calorie intake, and losing a little weight can help you lower your chances of developing type 2 diabetes. Taking the diabetes medicine metformin can also reduce risk, particularly in younger and heavier people with prediabetes and women who have had gestational diabetes. Lowering blood pressure and cholesterol levels also helps you stay healthy.

Decide how you will reward yourself—a shopping trip, movie tickets, an afternoon in the park—when you do what you have planned.

Your doctor, a dietitian, or a counselor can help you make a plan.

Be Physically Active Every Day

Regular physical activity tackles several risk factors at once. Activity helps you lose weight; keeps your blood glucose, blood pressure, and cholesterol under control; and helps your body use insulin. People in the DPP who were physically active for 30 minutes a day, 5 days a week, reduced their risk of type 2 diabetes. Many chose brisk walking as their physical activity.

If you are not fairly active, you should start slowly. First, talk with your doctor about what kinds of physical activity are safe for you. Make a plan to increase your activity level toward the goal of being active at least 30 minutes a day most days of the week. You can increase your level of physical activity in two main ways:

1. Start an exercise program.

2. Increase your daily activity.

Start an exercise program. Pick exercises that suit you. Find a friend to walk with you or join an exercise class that will help you keep going.

Do aerobic activities, which use your large muscles to make your heart beat faster. The large muscles are those of the upper and lower arms; upper and lower legs; and those that control head, shoulder, and hip movements.

Do activities to strengthen muscles and bone, such as lifting weights or sit-ups, two to three times a week. Find help—such as a video or a class—to learn how to do these exercises properly.

Do activities to strengthen muscles and bone, such as lifting weights or sit-ups, two to three times a week.

Increase your daily activity. Choose activities you enjoy. You can work extra activity into your daily routine by doing the following:

Increase daily activity by decreasing time spent watching TV or at the computer. Set up a reminder on your computer to take an activity break.

Take the stairs rather than an elevator or escalator.

Park at the far end of the parking lot and walk.

Get off the bus a few stops early and walk the rest of the way.

Walk or bicycle whenever you can.

Choose activities you enjoy.

Take Your Prescribed Medicines

Some people need medicine to help control their blood pressure or cholesterol levels. If you do, take your medicines as directed. Ask your doctor if you should take metformin to prevent type 2 diabetes. Metformin is a medicine that makes insulin work better and can reduce the risk of type 2 diabetes.

Eating, Diet, and Nutrition

Your eating, diet, and nutrition choices play an important role in preventing or delaying diabetes. Follow the suggestions below to reach and maintain a reasonable weight and make wise food choices most of the time. Remember that it can take time to change your habits and be patient with yourself. You can also get help from a dietitian or join a weight-loss program to support you while you reach your goals.

Reach and Maintain a Reasonable Body Weight

Your weight affects your health in many ways. Being overweight can keep your body from making and using insulin properly. Excess body weight can also cause high blood pressure. Every pound you lose lowers your risk of getting diabetes.

In addition to weight, the location of excess fat on the body can be important. A waist measurement of 40 inches or more for men and 35 inches or more for women is linked to insulin resistance and increases a person’s risk for type 2 diabetes. This is true even if your BMI falls within the normal range.

The NIH also has a free smartphone app for calculating BMI. You can search “My BMI Calculator” on your phone to find the app. The app also provides links to information about steps you can take to bring your BMI into a healthy range.

Body Mass Index Table

For a printer-friendly version of this table, use thePDF Version (410 KB).

Body Mass Index Table 1 of 2

Normal

Overweight

Obese

BMI

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

Height(inches)

Body Weight (pounds)

58

91

96

100

105

110

115

119

124

129

134

138

143

148

153

158

162

167

59

94

99

104

109

114

119

124

128

133

138

143

148

153

158

163

168

173

60

97

102

107

112

118

123

128

133

138

143

148

153

158

163

168

174

179

61

100

106

111

116

122

127

132

137

143

148

153

158

164

169

174

180

185

62

104

109

115

120

126

131

136

142

147

153

158

164

169

175

180

186

191

63

107

113

118

124

130

135

141

146

152

158

163

169

175

180

186

191

197

64

110

116

122

128

134

140

145

151

157

163

169

174

180

186

192

197

204

65

114

120

126

132

138

144

150

156

162

168

174

180

186

192

198

204

210

66

118

124

130

136

142

148

155

161

167

173

179

186

192

198

204

210

216

67

121

127

134

140

146

153

159

166

172

178

185

191

198

204

211

217

223

68

125

131

138

144

151

158

164

171

177

184

190

197

203

210

216

223

230

69

128

135

142

149

155

162

169

176

182

189

196

203

209

216

223

230

236

70

132

139

146

153

160

167

174

181

188

195

202

209

216

222

229

236

243

71

136

143

150

157

165

172

179

186

193

200

208

215

222

229

236

243

250

72

140

147

154

162

169

177

184

191

199

206

213

221

228

235

242

250

258

73

144

151

159

166

174

182

189

197

204

212

219

227

235

242

250

257

265

74

148

155

163

171

179

186

194

202

210

218

225

233

241

249

256

264

272

75

152

160

168

176

184

192

200

208

216

224

232

240

248

256

264

272

279

76

156

164

172

180

189

197

205

213

221

230

238

246

254

263

271

279

287

Body Mass Index Table 2 of 2

Obese

Extreme Obesity

BMI

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

Height(inches)

Body Weight (pounds)

58

172

177

181

186

191

196

201

205

210

215

220

224

229

234

239

244

248

253

258

59

178

183

188

193

198

203

208

212

217

222

227

232

237

242

247

252

257

262

267

60

184

189

194

199

204

209

215

220

225

230

235

240

245

250

255

261

266

271

276

61

190

195

201

206

211

217

222

227

232

238

243

248

254

259

264

269

275

280

285

62

196

202

207

213

218

224

229

235

240

246

251

256

262

267

273

278

284

289

295

63

203

208

214

220

225

231

237

242

248

254

259

265

270

278

282

287

293

299

304

64

209

215

221

227

232

238

244

250

256

262

267

273

279

285

291

296

302

308

314

65

216

222

228

234

240

246

252

258

264

270

276

282

288

294

300

306

312

318

324

66

223

229

235

241

247

253

260

266

272

278

284

291

297

303

309

315

322

328

334

67

230

236

242

249

255

261

268

274

280

287

293

299

306

312

319

325

331

338

344

68

236

243

249

256

262

269

276

282

289

295

302

308

315

322

328

335

341

348

354

69

243

250

257

263

270

277

284

291

297

304

311

318

324

331

338

345

351

358

365

70

250

257

264

271

278

285

292

299

306

313

320

327

334

341

348

355

362

369

376

71

257

265

272

279

286

293

301

308

315

322

329

338

343

351

358

365

372

379

386

72

265

272

279

287

294

302

309

316

324

331

338

346

353

361

368

375

383

390

397

73

272

280

288

295

302

310

318

325

333

340

348

355

363

371

378

386

393

401

408

74

280

287

295

303

311

319

326

334

342

350

358

365

373

381

389

396

404

412

420

75

287

295

303

311

319

327

335

343

351

359

367

375

383

391

399

407

415

423

431

76

295

304

312

320

328

336

344

353

361

369

377

385

394

402

410

418

426

435

443

Source: Adapted from Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report. National Institutes of Health, 1998.

If you are overweight or obese, choose sensible ways to get in shape:

Avoid crash diets. Instead, eat less of the foods you usually have. Limit the amount of fat you eat.

Increase your physical activity. Aim for at least 30 minutes of physical activity most days of the week.

Set a reasonable weight-loss goal, such as losing 1 pound a week. Aim for a long-term goal of losing 5 to 7 percent of your total body weight. To estimate this amount in pounds, find the weight closest to yours on the chart below. Follow the row across to see how many pounds you need to lose.

Make Wise Food Choices Most of the Time

What you eat has a big effect on your health. By making wise food choices, you can help control your body weight, blood glucose, blood pressure, and cholesterol.

Take a look at the serving sizes of the foods you eat. Reduce serving sizes of main courses, meat, desserts, and other foods high in fat. Increase the amount of fruits and vegetables you eat at every meal. Try using a small plate. For more help with choosing serving sizes, see the United States Department of Agriculture's website at www.choosemyplate.gov.

Limit your fat intake to about 25 percent of your total calories. For example, if your food choices add up to about 2,000 calories a day, try to eat no more than 56 grams of fat. Your doctor or a dietitian can help you figure out how much fat to have. You can also check food labels for fat content.

Talk with your doctor about whether you may drink alcoholic beverages. If you choose to drink alcoholic beverages, limit your intake to one drink for women or two drinks for men per day.

You may also wish to reduce the number of calories you have each day. People in the DPP lifestyle change group lowered their daily calorie total by an average of about 450 calories. Your doctor or dietitian can help you with a healthy eating plan that emphasizes weight loss.

Keep a food and physical activity log. Write down what you eat and how much physical activity you are getting. People who keep track are more successful in losing weight.

When you meet your goal, reward yourself with a nonfood item or activity, such as watching a movie.

Reduce foods high in fat and increase the amount of fruits and vegetables you eat at every meal.

Dietary Supplements

Vitamin D studies show a link between people’s ability to maintain healthy blood glucose levels and having enough vitamin D in their blood. However, studies to determine the proper vitamin D levels for people with diabetes and for preventing diabetes are ongoing; no special recommendations have been made about vitamin D levels or supplements for people with diabetes.

Currently, the Institute of Medicine (IOM), the agency that recommends supplementation levels based on current science, provides the following guidelines for daily vitamin D intake:

People ages 1 to 70 years may require 600 International Units (IUs)

People age 71 and older may require as much as 800 IUs

The IOM also recommended that no more than 4,000 IUs of vitamin D be taken per day.

To help ensure coordinated and safe care, you should discuss your use of complementary and alternative medicine practices, including your use of dietary supplements, with your doctor.

Hope through Research

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) conducts and supports research related to the causes, treatment, and prevention of diabetes. For example, clinical trials include The Avoiding Diabetes Thru Action Plan Targeting Pilot Randomized Control Trial (ADAPT). This trial is an innovative study that uses technology to affect lifestyle behavior change. This study is funded under NIH clinical trial number NCT01473654.

We now know that many people can delay or prevent type 2 diabetes through weight loss, regular physical activity, and lowering their intake of fat and calories. Researchers are working hard to understand the genetic and environmental factors that contribute to a person’s tendency to develop obesity, diabetes, and prediabetes. As researchers learn more about the molecular events that lead to diabetes, they will develop ways to prevent and cure different stages of this disease. Already, the DPP has shown that even in participants at higher genetic risk for type 2 diabetes, losing weight through lifestyle change lowered the risk of diabetes. DPP researchers continue to monitor DPP participants through the DPPOS to learn more about the study’s long-term effects.

Participants in clinical trials can play a more active role in their own health care, gain access to new research treatments before they are widely available, and help others by contributing to medical research. For more information about current studies, visit www.ClinicalTrials.gov.

As part of its Small Steps. Big Rewards. Prevent type 2 Diabetes campaign, the National Diabetes Education Program (NDEP) offers several booklets about preventing type 2 diabetes, including information about setting goals, tracking progress, implementing a walking program, and finding additional resources. These materials are available at www.ndep.nih.gov or by calling the NDEP at 1–888–693–NDEP (1–888–693–6337).

Acknowledgments

Publications produced by the Clearinghouse are carefully reviewed by both NIDDK scientists and outside experts. This publication was originally reviewed by David G. Marrero, Ph.D., Indiana University School of Medicine, Diabetes Research and Training Center, and Michael L. Parchman, M.D., M.P.H., associate professor, Department of Family and Community Medicine, University of Texas Health Science Center.

National Diabetes Education Program

The National Diabetes Education Program is a federally funded program sponsored by the U.S. Department of Health and Human Services’ National Institutes of Health and the Centers for Disease Control and Prevention and includes over 200 partners at the federal, state, and local levels, working together to reduce the morbidity and mortality associated with diabetes.

National Diabetes Information Clearinghouse

The National Diabetes Information Clearinghouse (NDIC) is a service of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The NIDDK is part of the National Institutes of Health of the U.S. Department of Health and Human Services. Established in 1978, the Clearinghouse provides information about diabetes to people with diabetes and to their families, health care professionals, and the public. The NDIC answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about diabetes.

This publication is not copyrighted. The Clearinghouse encourages users of this publication to duplicate and distribute as many copies as desired.

This publication may contain information about medications. When prepared, this publication included the most current information available. For updates or for questions about any medications, contact the U.S. Food and Drug Administration toll-free at 1-888-INFO-FDA (1-888-463-6332) or visit www.fda.gov. Consult your health care provider for more information.